Camera App Dropping Frames on iPhone 16 Pro Max

I have an iPhone 16 Pro Max 512GB. I have 91 GB free (as seen by the BM app). If I set the app to record 4K 60 FPS, I constantly get dropped frames after only a few seconds of recording. Sometimes the drop is for several frames, making the video unusable.

I have tried HEVC as well as ProRes 422. Bitrate is set at High (54 Mbps). I am recording to the internal iPhone storage, which I thought would be the fastest method. I do NOT get dropped frames with the default camera app or the Apple Final Cut Camera App at 4K/60.

I tried hard resetting the phone and trying the BM app immediately after the reboot. Dropped frames after like 5 seconds.

I have seen a bunch of conversations on here and other sites about external drive speeds and formatting, cables, power, etc. However, I am recording to the internal iPhone storage, so none of these are at play.

I would guess that the problem is the iPhone throughput can't handle recording 4K/60, but I never have dropped frames with the default app or the Final Cut app.

What am I missing?

I tried lowering the bitrate to 27 Mbps and STILL get dropped frames. For kicks, I tried ProRes 422 HQ in some short tests, and that did NOT result in any dropped frames.

I have now tested Filmic Pro at 4K/60 and it does not have any dropped frames in my tests. What is remarkable about the BM app, is that almost always I get the dropped frames within the first 5 seconds.

Seems like this is a bug.

[Peter Chamberlain]

Try turning off the proxy generation

Try turning off the proxy generation

I have exactly the same problem as the OP, but disabling proxy generation seems to have solved it.
However, I have not yet recorded over a longer period of time to see if the problem returns.
Thank you!

I tried disabling the proxies and the problem went away. I thought maybe the app can't handle writing proxies. But then I had to reset the app settings and forgot to disable the proxies. I recorded a video for almost 55 minutes the other day without any dropped frames (and proxies enabled). So now I have no idea what the problem was.